A warning ignored is an invitation for disaster, as the recent kidnapping and murder of four Americans by Somali pirates tragically illustrates. Just as the casual dismissal of a high voltage sign can result in a lethal shock, sailing in pirate-patrolled waters can prove equally fatal.

In 2010 alone, 1,181 hostages were taken by bands of these roving thugs, with eight reported deaths.

There are currently close to 700 people being held for ransom. With the average price being paid out reaching $5 million, kidnapping remains a lucrative activity for Somali pirates.

International trade depends on the free use of the seas, and trade vessels unavoidably remain targets. Recreational sailors, on the other hand, willfully disregard these statistics and continue to brazenly travel in areas known to be infested with marauders.

For the four Americans killed, overconfidence and a misguided sense of purpose proved deadly. Their fate should serve as both a grave tale of caution and an immediate call to arms.

On Feb. 18, the sailing yacht Quest was captured off the coast of Oman by Somali pirates.

Taken captive were a well-traveled group of friends consisting of Jean and Scot Adam, Phyllis MacKay and Bob Riggle.

Hardly naïve, they were well aware of the dangers they faced when they inexplicably decided to sail through the Red Sea, a known haven for pirates.

Soon after the initial assault, the US Navy responded, and for nearly five days tried to negotiate the Americans’ release.

Early last Tuesday, all hopes of rescue instantly vanished when gunfire erupted aboard the yacht, leaving the four Americans dead.

Afterwards, friends reported that the Adams were on a multi-year mission of distributing bibles and were dismissive of any dangers they faced.

The Adams intent may have been noble, but their beliefs caused them to act recklessly. In essence, they needlessly placed themselves in harm’s way under the pretext of service towards others.

Little did they consider that few messages could be spread if the messengers are killed.

Likewise, Phyllis MacKay and Bob Riggle expressed a somewhat cavalier attitude believing that they were prepared against any threats.

Exactly how they prepared against a dozen or more heavily armed militants was not detailed. Whether due to arrogance or self-delusion, they were terribly overestimating their ability.

While the murdered Americans carry a good deal of responsibility for their fate, they certainly did not deserve to be killed.

Their execution should serve as a rallying cry to international forces —that they should increase their efforts to eradicate these ocean-going terrorists.

First, no governing body should negotiate with the pirates. In all likelihood, this will initially result in more senseless killing as the pirates’ demands are refused.

However, once it becomes apparent that there is no possibility of financial gain, the motivation for kidnapping will dissipate.

Second, the US Navy and other nations should form a floating barricade in the international waters off the Somali coast, with explicit instructions to at least capture — and, if necessary, kill — any and all pirates.

Finally, attempts should be made to establish legitimate forms of commerce within Somalia itself.

A robust fishing trade is one possible option that would provide a sustainable alternative to piracy.

When given the option, most people tend to prefer legal means of earning a living over criminality.

In these times of global interdependence, there are simply no excuses for allowing barbarians to continue their tyranny over the open seas.